The invention relates to support apparatus suitable for use in a tube bundle. In another aspect, the invention relates to a tube bundle suitable for use in a shell and tube heat exchanger. In yet another aspect, the invention relates to the shell and tube heat exchanger. In further aspects, the invention relates to methods for tightening the tubes in in a tube bundle.
A major problem in the art of heat exchange is that of reliably supporting the tubes. The flow of fluid across the tubes in a tube bundle can induce vibrations of such magnitude that collision between the tubes themselves or tubes and tube supports can damage the tubes, or possibly even cause failure of one or more tubes. It would thus be very desirable to provide support structure for reliably supporting the tubes of the tube bundle.
One type of support structure known to the prior art involves the use of plate baffles. The baffles are provided with apertures therethrough with the tubes extending through the apertures. With plate baffles, however, it has proved very difficult to provide a sufficiently close fit between the outside of the tube and the inside of the aperture of the baffle in order to prevent the possibility of vibration induced damage between the tube and the baffle. Where clearances are precisely controlled, other problems can arise. Where insufficient fluid flows through the annulus between the baffle and the tube, localized overheating and vaporization of the fluid can occur with the deposition of solids when present. The solids can promote corrosion of the tubes and, in some events, lead to failure of the tubes. In other instances, the solids can build up in the annulus and expand to the point that fluid flow through the tube is impaired due to partial collapse of the tube. It would clearly thus be very desirable to provide a tube support means in which positive tube support and minimal risk of localized overheating, boil out and crevice corrosion are provided.
Another problem frequently encountered in the art is that of excessive pressure drop through the shell side of the tube bundle. Support structure extending through the bundle in a direction perpendicular to the direction of fluid flow can cause considerable pressure drop longitudinally through the bundle. As a general rule, pressure drop through the tube bundle increases with increasing volumes of tube support elements and an increasingly perpendicular orientation of the tube support elements to the fluid flow. The extent to which the tube support elements are streamlined is also an important factor. It would be clearly desirable to provide tube support apparatus which reliably supports the tube with minimal pressure drop of shell side fluid flowing through the tube bundle.